CIP Suite — EtherNet/IP Node

A CIP Suite node for communicating with Rockwell Automation and Allen-Bradley PLCs using the EtherNet/IP (Ethernet Industrial Protocol) protocol.

Overview

This node provides a robust interface for connecting FlowFuse flows to industrial control systems, specifically Rockwell Automation and Allen-Bradley programmable logic controllers (PLCs). It wraps the st-ethernet-ip library to enable real-time tag monitoring and data collection from industrial automation equipment.

What is EtherNet/IP?

EtherNet/IP (Ethernet Industrial Protocol) is an industrial network protocol that adapts the Common Industrial Protocol (CIP) to standard Ethernet. It's the primary communication protocol used by Rockwell Automation and Allen-Bradley industrial controllers, including:

• ControlLogix PLCs
• CompactLogix PLCs
• MicroLogix PLCs
• PowerFlex Drives
• PanelView HMIs
• Other Rockwell Automation/Allen-Bradley devices

How It Works with Rockwell/Allen-Bradley Hardware

This node establishes a client connection to Allen-Bradley PLCs over EtherNet/IP and provides the following capabilities:

1. Controller Discovery

When connecting, the node automatically:

• Reads controller properties (model, serial number, firmware version)
• Discovers available tags in the controller
• Retrieves controller time and status

2. Tag Subscription

The node subscribes to specific tags (variables) in the PLC and monitors them for changes:

• BOOL tags (Boolean/Digital I/O)
• DINT tags (Double Integer/32-bit integers)
• REAL tags (Floating-point values)
• STRING tags (Text data)
• Custom data types (UDTs)

3. Real-Time Monitoring

• Polls the PLC at a configurable scan rate (50ms to 36000s)
• Emits messages only when tag values change
• Maintains a cache of current tag values
• Handles Allen-Bradley string encoding (82-character strings with 4-byte length prefix)

4. Connection Management

• Automatic connection lifecycle management
• Proper cleanup on deployment or shutdown
• Error handling and status reporting
• Support for different slot configurations (backplane addressing)

Installation

Because this node is part of the FlowFuse Edge Certified Nodes add-on, make sure your account has access before installing. Contact our sales team if you don't.

Install via the Palette Manager (recommended)

1. Open the Palette Manager from the top-right menu in the FlowFuse editor.
2. Switch to the Install tab.
3. Search for the FlowFuse Edge Certified Nodes collection.
4. Locate @flowfuse-certified-nodes/cip-suite and click Install.

Install via npm

If you manage your palette from the command line, install the package directly:

npm install @flowfuse-certified-nodes/cip-suite

Usage

Input Message Format

Send a message with the following payload structure to initiate a PLC connection:

{
  "address": "192.168.1.100",
  "slot": 0,
  "scanRate": 500,
  "tagConfig": [
    {
      "scope": "",
      "tags": [
        {
          "tagName": "ProductionCount",
          "tagType": "DINT"
        },
        {
          "tagName": "ConveyorRunning",
          "tagType": "BOOL"
        },
        {
          "tagName": "Temperature",
          "tagType": "REAL"
        },
        {
          "tagName": "PartNumber",
          "tagType": "STRING"
        }
      ]
    }
  ]
}

Configuration Parameters

• address: IP address of the PLC (required)
• slot: Backplane slot number where the processor is located (typically 0 for CompactLogix, varies for ControlLogix)
• scanRate: Polling interval in milliseconds (50-36000000ms)
• tagConfig: Array of tag scopes containing tags to monitor
  • scope: Tag scope in the controller (empty string for controller-scoped tags)
  • tags: Array of tag objects
    • tagName: Name of the tag in the PLC program
    • tagType: Data type (BOOL, DINT, REAL, STRING, etc.)

Outputs

Output 1: PLC Data

Emits updated tag values when changes are detected:

{
  "payload": {
    "ProductionCount": 1250,
    "ConveyorRunning": true,
    "Temperature": 72.5,
    "PartNumber": "ABC-123-XYZ"
  },
  "changedTagName": "ProductionCount",
  "changedTagValue": 1250
}

Output 2: Debug/Metadata

Provides diagnostic information and PLC metadata:

{
  "payload": {
    "category": "plcProps",
    "value": {
      "name": "CompactLogix Controller",
      "serial": "12345678",
      "slot": 0,
      "version": "31.011"
    }
  }
}

Categories:

• plcConfig: Echoes the input configuration
• plcProps: Controller properties (model, serial, etc.)
• plcTime: Controller clock time
• plcTags: Complete list of available tags
• debug: Diagnostic messages
• error: Error information

Connection States

Monitor the node status to track connection health:

Example Flow

[
  {
    "id": "inject1",
    "type": "inject",
    "name": "Connect to PLC",
    "topic": "",
    "payload": "{\"address\":\"192.168.1.100\",\"slot\":0,\"scanRate\":500,\"tagConfig\":[{\"scope\":\"\",\"tags\":[{\"tagName\":\"Tag1\",\"tagType\":\"DINT\"}]}]}",
    "payloadType": "json",
    "wires": [["plcNode"]]
  },
  {
    "id": "plcNode",
    "type": "eth-ip",
    "name": "Production Line PLC",
    "wires": [["output"], ["debug"]]
  }
]

Best Practices

Connection Management

• Any new input message will close the existing connection and establish a new one
• Use a status node to monitor connection health and implement retry logic
• Handle reconnection logic externally to the node

Network Configuration

• Ensure your FlowFuse instance can reach the PLC IP address
• Configure firewall rules to allow TCP port 44818 (EtherNet/IP)
• Use static IP addresses for PLCs in production environments

Tag Selection

• Only subscribe to tags you need to minimize network traffic
• Use appropriate scan rates based on how quickly data changes
• Faster scan rates increase CPU and network load

Error Handling

• Connect a catch node to handle errors gracefully
• Monitor the debug output for diagnostic information
• Implement reconnection strategies for production reliability

Compatibility

Tested Hardware

• Allen-Bradley ControlLogix (L7x, L8x series)
• Allen-Bradley CompactLogix (L1x, L2x, L3x series)
• Allen-Bradley MicroLogix (1100, 1400, 1500 series)

Supported Data Types

• BOOL (Boolean)
• SINT (Short Integer)
• INT (Integer)
• DINT (Double Integer)
• REAL (Floating Point)
• STRING (82-character Allen-Bradley strings)
• Custom UDTs (User Defined Types)

Troubleshooting

Cannot Connect to PLC

• Verify IP address and network connectivity (ping test)
• Check slot number matches your controller configuration
• Ensure PLC firmware supports EtherNet/IP messaging
• Verify firewall settings allow TCP 44818

Tags Not Updating

• Confirm tag names match exactly (case-sensitive)
• Verify tag scope is correct
• Check scan rate isn't too slow for your application
• Ensure tags exist in the controller

Connection Drops Frequently

• Reduce scan rate to decrease network load
• Check network stability and switch configuration
• Verify PLC isn't overloaded with connections
• Consider using unconnected messaging for multiple clients

Technical Details

This node uses unconnected messaging mode by default with a 5064ms timeout, which:

• Reduces timeout issues with multiple clients
• Works better in high-latency networks
• Allows multiple nodes to connect to the same PLC

String handling automatically decodes Allen-Bradley's proprietary format:

• First 4 bytes contain Little-Endian INT32 length
• Remaining bytes contain ASCII character data
• Maximum length of 82 characters